This invention relates to a latching disabling circuit useful in conjunction with an oscillator in a television receiver.
In many television receiver circuits, various oscillator circuits perform necessary functions for normal receiver operation. For example, the horizontal oscillator provides drive signals to an output switching device such as the horizontal output transistor. Should the oscillator be disabled, scanning will cease, and any supply voltages, such as the high voltage ultor supply voltage, will be removed. Similarly, many receivers provide B+ power supply regulation by conduction angle modulation of a controllable rectifier. An oscillator will typically provide switching signals to the controllable rectifier. If these signals are blocked, the B+ supply will be disabled.
For safety purposes, under various fault conditions, such as excess high voltage or current overload, disabling of the regulator or horizontal oscillator will disrupt normal television receiver operation or completely disable the receiver, removing the fault condition until circuit repairs are made. It is desirable to provide an oscillator disabling circuit that is readily adaptable for use with various oscillators, that involves a minimum of design modifications to existing circuits, and that uses a minimum of additional components.